Analysis of the debris-flow hazard on the Rioulong torrent (Hautes-Pyrénées, France) alluvial fan using a scenario-based approach

Abstract

A method of debris-flow hazard analysis, using the Cemagref LAVE2D model, within a scenario-based approach, is applied to a torrent of the French Pyrenees. A preliminary analysis of the catchment shows that some risk of debris-flow occurrence is present and that scenarios should be constructed accordingly. Numerical simulations are carried out on the basis of these scenarios. They produce maps of maximum extension of debris flows in relation to qualitative levels of probability of occurrence. Simulations also provide information that is useful for the design of a protection structure. Finally, the maximum extension of debris flows resulting from the presence of the protection structure is analyzed.